Method and apparatus for form milling resinous blanks



Oct. 26, 1943.

P. WILLIAMS ET AL METHOD AND APPARATUS FOR FORM MILLING'RESINOUS BLANKS Filed Jan. 18, 1941 25 2- fiMA/KPMu/AMS m CHaRLEs VJSMITH, N

. derivatives of acrylic and methacrylic acids.

Patented Oct. 26, 1943 METHOD AND APPARATUS FOR FORM MILL- -ING RESINOUS BLANKS Frank P. Williams and Charles v. Smith, Dayton, Ohio, assignors to The Univis Lens Company,

Dayton, Ohio, a corporation of Ohio Application January 18, 1941, Serial No... 375,089

1 Claim.

This invention relates to a method and apparatus forshaping the edge of disk-like articles.

formed from plastic materials. This invention is particularly applicable for. shaping disks of plastic material which are to be used as lenses, and is of special value when chamfering and shaping ophthalmic lenses. i t i When manufacturing lenses, or other disk-like articles which are to be fitted within a frame, it is particularly convenient, for assembling the disk-like article into a frame, if the article be chamiered in a manner that the angle of chamfer remains constant with respect the axis of the disk. Heretofore it has been the common practice when assembling disk-like articles into frames, and particularly when assembling ophthalmic lenses into metalframes, to shape the article to the desired configuration and then to chamfer the edges thereof sothat the chamfer will be even over the entire edge of the article. When assembling such disk-like articles it has been necessary to deform the frames to agree with the curvature of the edges of the disk-like article. This is particularly true when placing ophthalmic lenses in frames since these lenses many times have prisms formed therein, or have a cylinder imposed upon a sphere to obtain the proper lens correction desired. Thus, when manufacturing such lenses the configuration of the edge of the disk-like article or lens varies considerably and if the chamfer of the edge of the article remains constant around the edge thereof, it can readily be seen that the frame which surrounds the lens will be required to be deformed to an extent which will agree with the configuration of the edge of the 'lens. This fOrm of practice requires individual manipulation of the frame to a particular lens, and thus entails considerable handwork and skill to properly assemble an ophthalmic lens in a metalframe.

This invention has been developed to remove these former'disadvantages and to simplify the manner in which the lens can be shaped and the edges thereof chamfered. As is well known, ophthalmic lenses heretofore produced have always beenmade of optical glass andthus have required intricate and complicated devices for grinding the edge configuration of the lens and for chamfering the edges thereof. The applicant, by this invention, eliminates thernecessity for complicated edge shaping and chamfering devices since the applicants form the lens from'a synthetic plastic material, such as the organic resins produced by the polymerization of the monomeric The substances which .have. properties suitable for optical purposes, such examples as Crystalite,

Lucite, and Plexiglas, are known tothose versed in the art of lens manufacturing. Articles made from the artificial resins can be shaped andcut more easily than the articles made from glass, hence it is an object of this invention to provide a method and apparatus wherein ordinary milling cutters are used to shape and chamfer a diskv of plastic material.

I It is another object of "the invention to provide an apparatus whereina disk of plastic material is rotated slowly with respecta milling cutter, and in engagement therewith, so that the periphery of 1 a plastic disk can be shaped by a single revolution thereof.

1 It is another object of the invention to rotate a milling cutter in engagement with the edge of a disk of plastic material to shape the same, the degree of engagement being controlled by 8.1 form pattern.

It is another object of the invention to chamfer the edge of a disk-like article of plastic material concomitant with shaping the article to its final outline shape. a I

It is still another object of the invention to "chamfer the edge of an irregularly shaped disklike memberfo-rmed of plastic-material in a manner that the chamfer angle remains constant with respect the axis of rotation of the disk.

It is still" another object of the'invention to chamfer bothedges of an irregularly shaped disklike article formed of plastic material So that the angles of chamfer remain constant with respect the axis of rotation of the disk, and thus form the sides of a triangle the apex ring of which,

' formed around the edge of the disk, lies ina plane.

. vide a method for shaping an ophthalmic lens provide a method for shaping an ophthalmic lens in accordance with foregoing object wherein the edges of the lens are chamfered concomitantly with the shaping operation.

Further objects and advantages will become apparent from the drawingand a reading -of th description.

In th'e'drawing:

Figure 1 is a plan view.of axmachinefor performing the operation of this invention.

Figure 2 is a perspective .elevationalview of.a

portion of the machine disclosed in 'Figure "1.

Figure 3 is a face view of a lens or cidisknlike article formed .on the machine.

.f-Figuref l is an edge View ofthe "disk-like Tar gticleor lens shown I'in' Figure 3, and" shows the -mannerjin .whichthe .apex iii 'chamiered edgeliesglin a plane. f a

, ".Eigur'e .15 is .a. partial gcross-sectional "View of .ailens. mounted within. a .frame.

.lEigure 6..is,an .levationa'l viewj'of. the cutting .mechanismflfor. shaping'lthe outline of a disklike article, and shows a mo'difieTdgarrangement which. performs ..the. shaping .operation.

, .lIhisinveritiomrElates ,particiilarlyito ..app'ara- .tus which is used.inthemanufacture. of lenses ifromisynthetic plastic resins. 'TWhileihe'inventhe shaping of the outline of '1enses,wandf.the ..chamfering-.of ..the .edges thereof, .it will Jeevun- :.-.,derstood..that; the. invention. is, ,ijustvas applicable to thev shaping. and wohaniieringa of. any disk-like articlewwhichais termed-from.a syntheticsplastic material.

- .The invention hasqparticular merit .With vrevgardthe edging-and zchamfering. of w-Qphthalmic .-lenses. .It.risiwelltknownathat ophthalmic lenses have diiferent shapes, thicknesses "and @Various.

- curvatures according-towvhetherxa prism, icylinder, orr ephere, tor -;1a;-combination=, of these'l configurations i-is :rirnposed appon the lensuto secure --ithe .gpreper: correction; at 21'8"73130 common :to

shape thepperimeter ofa'thealens. ifl;S0me?0dd 0On- :figura'tion .-;in o.rder :to .-enhance-;the' iappearance tithe 'Iln'ns. x i-Since rthe .lens ehns ibot'h; 'assuriace :icunvatu-re and; arnmddz:perimeter zeonfigurationlit :hasipreviouslylbeen:"necessaryrto msescomplicated machinery to both shape the iperimeter zoft themany times usedaround the lens -to support the A *sameg'be formed by' -hand orlby propermanipulation"of tools to form the iram'e to the oonfi'gu'ration of 11 the lens. ass -required; considerable manual rnanipulation of frames and has entailed considerable expansion.

In this invention theaapplicant is setting forth a methed" and an apparatus which -eliminatesrthe previous aexpensive p'ra'o'tices :and considerably simplifies the-=manner in -which therperiphery of the lens can' be'shapedaana iihani-fered.

Since the applicants are producing lenses from synthetic plastic materials he can use milling cutters for shaping the lens and chamfering the same, which cutters have heretofore been impossible of use when shaping or forming lenses of glass.

, 'I Zhemachine .discloseclherein is,some.what diagrammatic inf its construction; howeverzall of the essential features required to perform the shaping and chamfering operations are included in the "disclosure, it being readily understood that the fi-mechan'ism'can take various forms. and that *va'riousmiechanical alterations can be made in .the,.apparatus-without departing from the spirit vor scope of the :invention.

-;.The apparatus 'consists of the base it) upon which bearing members II are securely positinned. Ashaft-IZ is journaled in the bearings II and is provided with a pulley 13 over which a belt M extends. The belt [4 cooperates with the pulley l5 which is mounted nafsha'ft F6 extend- *ing'from thegear box 1-? -"Apair*of--milling=cutters +8 is mounted upon the-shaft f2 *and haVe hub extensions I 9 which are secured to'the "shaft 'EZbymeanSof'the setscrews -28. "In'the' apparatus disclosed in this invention, it is'proposed that two milling cutters 18 of like'angularfacecon- "figuration shall be placed Ill! engagement with each other so "that a*v=shaped milling groove :is provided. "Ihe cutters "18 are adjustable; axially upon'tthe shaft 'l2"since the set ScrewsiZil can readily be loosened to permit'shi'fting ofthe cuttersalong the'sha'ft'IZ. I j a 'A' second. shaft T21 "is arranged parallel with respect lthe shaft 12 .and.is;journaled in the bearings ZZWhich are'suitably'securedtothebase L0. The shaft"?! carries .a. pulley;f23 over which the "belt' fl extends. "I'he gear boxfl'is provided with a second extending 'sha'ft"'25 npon'the end of which there is providfdthepulley-.26 over whic the'belt'24 extends. v

electric, motor *2! "has the L'clriving sha'ft thereof extending in'to the. gear .box 1 ill andv is in suitablygeared connection Wfithltheshafts wand '25. "Theiinterna'l nle'hanismv of.the.,gear' box [.7 is. so. arrangedthat 'theshaft .[6 will rotate .ata .-higher speed than the shaft 15,..viherby the shaft .l2 ..will..lee-rotatedl at .-a ,l'higher speedthan .the .shaft 2,l'.- 1

:pair, of pivot .blocks 28 lan'dzfiais. carried .upon -.the shaftizl in a,.manner that-theyican freely rotate-thereon. The ;pivot' blockt23. is; prevented iromiaxialsnovement alonglthe shaftllabylmeans of the collar .39; anduthe hub-lot the gear. 3 l, ,avhich .ggear is properly secured .to;the shaft,-2i. iI-Yhe -.pivot block :39 FlS similarly .secu1ed1-fi'om:axial -:movement along-the shaft 21 .bYYIHQHXlSIOfithQiCOI" 'lar-;32iand;the hub of-zthe .gear.-33.

- The' pivot .blockr28 whaexashasft :6 ..iournaled therein, 21113011120118 -end.:of iWhiCh' therezis :fixedly positionedthe 2 gear '35 1 which: :is in engagement :with-th'e gear: 31. .The'oppositeiendof theshaft r34 1 carries ;'a friction :shoe ,r-fifi-avhieh 221's slidably mountedc upon theshaftafl andtzai's. retained-from complete removaltfromrthersha'ft 34 rbyia suitable fastening-imeans-onrthe endtheredf. .LAzcompres- .sionrrsprin memberaffl l-"surrounds .=the.:shaft.;34

-'I 'h'e pivot block 29 carries a' shaft 4| journaled 'therein which-is prevented from axial movement within the pivot block 29 by means of the collar 42 positioned within the 'pivotblock and suitably secured to the s ha ft'4 l." One "end ofthe shaft 4| carries agear 43 which is infrnesh With the gear 33 on the shaft 2 I 'l'he opposite end of the shaft 4| carries a friction shoe 44 which is fixedly mounted upon the shaft4ll- V The shafts 34-and 4| are thus drivenfrom the shaft 2| through the 'gears 3|, 35, 33 and 43, which gears are arranged to drive the shafts 3'4 aud t at the same speed so that a disk 45 positi'oned" between the friction shoes 36 and 44 will b eiotated. "I'he spring 31 moves the fric- "tion'shoe -38"in a"rightward direction to cause frictional engagement of the disk 45 with the shoe 44 whereby the disk 451s retained by spring pressure in position between the shoes-35 and 44 so that the shafts 34 and 4| can rotate the same ters |f8'. v i i f To retain the disk 45 in engagement with the milling cutters I8 the pivot block 28 is provided at a"prop'er speed with respectjthe milling cutwith an extending arm 46 upon which there is a weight l'L'fThe weight 41 issecured upon the arm' by means of a set screw". As heretofore mentioned the pivot blocks 28 and 29 are suitably pivoted upon the shaft 2| so that the weight 41, which is eccentric with respect the vertical "axis of the shaft 2|, will rotatethe pivot blocks 28 and 29 in a manner to cause the disk 45 to engage the milling cutters I 8. The degree of pressure by which the'disk 45 engages the milling cutters |8' can be controlled by the positionmg of the weight '41 along the rod 46.

To control the degree of engagement of the disk 45 with' the milling cutters IS a form patterm is carried upon the shaft 4| and i provided with a hub 50 which is detachably secured to the shaft 4| so that form patterns of different peripherahconfi'gurations can be placed upon the shaft 4|." An angle plate is positioned adjacent-theform pattern! and against which the form patternw will'be urged by means of the weight 41 pivoting the pivot blocks 28 and 29 "aboutthe shaft 21. v

FIt may now readily be seen that whena form pattern of a particular peripheral configuration is placed upon the shaft 4|, and the shaft M1 is suitably rotated while the disk 45 is held in engagement with the milling cutters l8, which are aIso rQtated, thatuaxial rotation of the disk '45 will cause the millingcutters Hi to remove material from the peripheral edge of the disk 45 in a manner that the form pattern will be :reproducedupon the disk, The speed of rotation of the milling cutters I8 is considerably higher,

than, the speed of rotation "of the disk .45; In

fact, the disk 45 is adapted to be. rotated once andupon completion of rotationthe milling cutters l8 will have removedall of the excessmaterial from the edge of the "disk 45 so thatthe form pattern 48 will be ,reproduced upon the disk.

4 Such a high speed and rapid removal of aterial-from thedisk 45 is possible since th disk 45"is-made from a synthetic plastic material,

which material can'be worked with the same machine tools ascan work wood or metal, and can belworked in the same manner and at substantiallyxthesame' highspeedso'f working.

The angle plate 5| is adjustable upon the base |||1 by means-of .the, bolt' 52 extending through athe,lslot'v53yprovidedin the base l0. ,Movement ,ter disclosed in Figure 1.

of the angle plate 5| with respect the shaft 2| permits the pivot blocks 28 and 29 to rotate about the shaft 2| in a manner to carry the shafts 34 and 4| into closer relation with the milling cutters |8 so that form patterns of different sizes can be positioned on the shaft 4| to produce disks of difierent diameters, but will have produced thereon the same peripheral configuration as the form pattern 49.

While the apparatus herein discloses a gravity weight 41 which retains the form pattern 48 against the angle plate 5| and th disk 45 against the'milling cutters l8, it can readily be seen that other means can be used for urging these elements in cooperating working relation.

Such other means would readily be a spring, or some type of air pressure control, or any other means for urging rotation of the pivot blocks 28 and 29 about the shaft 2|.

The machine as heretofore described has been disclosed as an apparatus for forming the peripheral outline upon a disk or blank of resinous material 45. This'blank45 can be either a plain flat 'disk or can be an ophthalmic lens, or any other disk of resinous material upon which. a particular outline is to be reproduced.

The apparatus is also capable of performing the function of chamfering the edges, of the disk, which chamfering can be performed either after the shaping operation or concomitantly with the shaping-operation. If the chamfering is to be done after theshaping operation then the first operation will be the shaping of the disk 45 by means of a flat milling-cutter, as disclosed in Figure 6, and the chamfering operation will then be performed with a V-shaped'milling out- However, both operations can be conveniently carried out at the same time by the use of the V-shaped milling 'cuttersdisclosed inFigure 1. i

To chamfer the edge of the disk 45, thesubstantial' median point of the edge of the disk is positioned in alignment with the apex of the V provided by the milling cutters I53. As here'- tofore stated, the frictionshoe' 44 is fixed upon the shaft 4| so that the pressure of engagement of the shoe upon the disk 45"wi1li'1retain the same in proper axial position with respect the milling/cutters "I8 and the V-shaped cutting faces formedntherebyp v If the resinous disk 45is merely a elementfthe rotation" of the disk by means .of

the shaft 4| will permit themilling cutters? |8 tocut or shape the edge of thedisk 45 ina "manner'to produce a triangular shaped edge surface thereon, whereby the apex ring'formed by the angular shape of the edge will lie in'a plane.- Under these circumstances theflapexof the edge 'sur facewill be concentric with respect the axisvof the disk, if the disk is atrue circle, The angle of chamfer remains constant with reprovide a V-shaped edge out for the disk 45, the

edge of the disk willbe chamfered as heretofore described. ,p-However, the apex of the chamfered edge of the disk will'not be concentric with the flat" disk =45. These flat.-disks=14-5, icommonlyknown as eplanos cantbe used for safety go les, sunglasses, and :other articles =-not.-requiring' 1ens curvature. ill} 1 is thuszseen that since the schamfered edge of wthe disk is v "arranged in 7a rmanner that the apexrof'athe "chamfen-liesein a plane that-thedisk 'e'an .begplaceidinia frame without'deformation f thelfmme. I 3

When shaping' a Ndisk 30f resinous ,material which has a :curved' face, -such-as =a--disk ifor an lophthalmic lens, or at planoxwhich hasia .curved surface, @and which-is2tome "imparted. with an :ndd configuration, :such :as Tgtheform pattern-49, it:eanv-bez'seeirthat :the edge of .-;the resinous [disk will not always :main'tain 'wa'glposition at right angles :to the a a-Xis of: rdtation-rof the 1' disk. tSuch an article of manufacture. is-rrepresentedwby-Figures13, 4 and '5, wherein :lthe zresinous diskflfi :is provided with a flattened -ed'ge'eontourwasFindimentiwith' the milling *cutters' lflby means of the ahout the ishaftilzl. Theformipattern 4% which is to Joe reproduced upon the disk 45, is'placed -=l1p6n the end 0f "the Sl'ltftfl' and retained in engagement with'th-e angle .platel in :a manner heretofore described. l lhe shafts i112 and .21! are rotated "by .m'earis "of the :driving gear "box 111, Qitiven by-the-m'oto'r 21, so'tha'tithe milling cutters 11B are rotated 'atia irlatively high speed while the resinous blank45 is :rota'ted at a very low speed with respect the milling cutters '18. In rraet',:it :is the purposeof the invention to remove all dfthe excess of the edgezmaterial of the disk 45 by means o'f the m'illin'g fcuttersiIB upon one complete revolution "of'ithe disk '45, whereby the edgecoiitour'will beiimparted to the disk'as Well as a'fpredeterminedshape;

iItmahBreadily be seen thatfrotation of the disk 545, While in continuous :engagement :with the milling cutters l8, and undera -"controlled engagefmentby the forrn pattern '49 willreproduce the form ipat'tern upon the resinous disk "45.

' Since, as heretofore mentioned, the xdisk= 45 hasamdrvedsurface thereto; or canihave a Jprism or eylinder -impartedupon the'curvedsurface of th-e disk r to produce an "ophthalmic lens, itmay be seen thatwhile th' disk is rotated upon its axi s thats the edge thereof will not-always maint'aina right angular relation withthe axis.

flhissc'hangingaangular relation of the edge of the disk with respect the milling cutter 1'8 will alter the degree ofthe cut removed from the edges-dt'the d-i'sk 45'as itliS rotatedin engage- -mentwith'the milling cutters.

' As shown in Figure '4, agreater quantity of Y a "triangular sha wherein the .-:apex f :the :V- Rshaped ringwill lie "in =a;plane, .even thoughthe movement of. the;edgersurfacefof-zthedisk: changes its angular relation "with (respect thetnnilling cutters. .This isaccomplishedsince I the cutting faces. of the milling cutters -=1-8 maintain :a. :fixed angular-relation with respect the axisof rotation of the resinous disk sec that regardless-of the contour of the periphery tor-be -reproducedeupon the edge of the.disk-45 the Al-shaped :edgenwill be acontinuous straight line around the ledge surface. I 7

Such 'a "chamfering ef theeedge surface: of-t-he resinous disk 45 permits-the-zdisk-ltobe placedz-in a 'V -shaped' metal frame 55;.-as disclosed'indiigure 5, :theframe beingi previouslyrpre-formed' tO'sthB :proper peripheral contour but having the W- shaped-retaining edge thereof arranged in a plane. It may thus 'bew'seen :that the Ireslnous disk, 'or ophthalmic lens -45-,-:ean vthus f be :easily assembled-Within: the framer55mrithoutmequiring hand manipulation of the frame to fit the particular requirements ofithe lens being :positioned therein. I

The apparatus :herein describedthus provides a" machineanda. methodaforishaping the periphery: of a resinous diskrof material, which: can be either a common fflatzdiskror ian: ophthalmicrlens in a rna'nner that the material can doe readily work-ed and shaped by the usemfmordinaryrmill- ;ing cutters. The method andaPpar-atus :also -providestheedge-of-ithe shapeddiskwith a-chamfer which is-shaped to permit easyaassemblyofithe -disk into a frame without manipulation -.of tthe .lens frame to fit thegparticular :lens.

As heretofore mentioned, Figure i6=..disoloses.-an 1 apparatus -by-which= thexresinousz disl 45;-is:,pro- .vided with a peripheral contour ofgpredetermined shape, but the edges-thereofiarenot-.ehamfered. In this arrangement rthe emiilingcutters [8 were .rreplaced withwaflat-millingicutter 56 whichds *mounted uponithe shaft t2ro'futhe:mashinehere- -to'fore:described. The-'resinouskdisk 45a ismstained between rthe :frietion sshoes $6 and M mounted upon zthe =shaft 4-1 --.of ':the :machine was heretofore describedrandsis retained inengasement with the milling cutter fifi :in the same manner as the disk (45: is'retained inzengagement :with'themilling cutters l8. lhe'formipatternrdfi earries the shaft Mil .throughtheesame type of motion "as previouslylreferred to :in order -;to reproduce the contour thereof upon the-resinous disk 35a. "Since "theimillm'gzcutter .56 rhasrazfiat cutting surface, thes ed'ge ilif ithe .id-isk 45 will be shapedin'peripheral contour only.

"The apparatusiherein disclose'cl and:descr'ibed simplifies the 'operation of -"shaping the "contour "of a blank-of resinousm'ateria1 Whichisto be 'used asa'lens, and particularlythose planks 'of "resinous "material whichareto beused "as oph- 'tha lmiclenses s'ince"thecontour-of bphthalmic 'lenses is changed .to meetvariousiindividual:requirements for purposes "of appearance. While the contour of theophthalrnic lenses'is Changed yet it isdesirablethat .all.of .the .various icontours can .be readily assembled within framesoof predetermined contourwi-thout-the requirement of individual .manipuiationzand bending of the iframes to fit -the;partieular lens requirements. Thus this inventionxsimplifies the assemblingrof lenses in framesuof predetermined :contour, since the edgezof theilens' by whihwthe same willbe iretained within lthe frame isrfof iunitermi config :uration to fit any len's frame having 'tlreisame contour and the same uniform configuration or edge retaining surface.

Having thus fully described our invention, what we claim as new and desire to secure by Letters Patent is:

An apparatus for shaping the edge of a disk of resinous material having a curved surface and for simultaneously chamfering the opposite edges thereof during one complete revolution of said disk comprising means axially supporting and rotating a milling'cutter having opposed angular cutting faces at a high speed, means supporting said disk with the axis thereof parallel to the axis of said cutter for axial rotation at a relatively low speed as compared to the speed of rotation of said cutter, a form pattern associated withsaid supporting means, means for concomitantly rotating said disk and said form pattern to cause the edge of said disk to follow a path generated by the rotation of said form pattern, means urging the edge of said disk into engagement with said cutter to cause removal of material therefrom in conformitywith the form pattern and simultaneously chamfer opposite edges of said disk concomitant with said shaping during one revolution of said disk, and means to prevent axial displacement of said disk with respect said cutters whereby the angles of chamfer form the sides of a triangle the apex ring of which lies in a plane. i

FRANK P. WILLIAMS,

CHARLES V. SMITH. 

